1. Field of the Invention
This invention relates to preparing derivatives of organic sulfonimidic acids. More particularly, this invention relates to a novel, convenient method for preparing N-silylated organic sulfonimidoyl halides from the corresponding N-silylated sulfonamides using readily available or easily prepared reactants.
2. Background Information
Organic sulfonimidoyl halides can be represented by the general formula R.sup.2 N.dbd.S(O)(R.sup.1)X, where R.sup.1 represents a monovalent substituted or unsubstituted hydrocarbon radical and R.sup.2 represents a hydrogen atom or a hydrocarbon radical.
Prior art methods for preparing sulfonimidoyl halides use tetravalent sulfur compounds as starting materials. For example, Levchenko et al. [J. Org. Chem. U.S.S.R. 1, 1251 (1965) and 3, 1439 (1967)] describe the preparation of sulfonimidoyl halides by the reaction of aryl sulfinyl chlorides of the formula ArS(O)Cl with N,N-dichloroalkylamines, their sodium salts or N-chloroamides.
The preparation of alkane sulfonimidoyl halides by the oxidation of the corresponding sulfinamides using chlorine, t-butyl hypochlorite or N-chlorobenzotriazole as oxidizing agents is reported by Carl Johnson [J.O.C. 44, 13 (1979)].
T. Bechtold and A. Eingelbrecht in the Journal of Fluorine Chemistry [19, 379-402 (1982) describe the preparation of N-trimethylsilyl trifluoromethanesulfonimidoyl chloride by the reaction of trimethylsilyl azide with trifluoromethanesulfinyl chloride.
Compounds of tetravalent sulfur useful as reactants for preparing N-silylated sulfonimidoyl halides are not readily available. The sulfinyl chlorides used by Levchenko and Johnson are not suitable for preparing sulfonimidoyl chlorides for a number of reasons, including (1) the alkanesulfinyl chlorides used by Johnson cannot be stored for long periods of time in unvented closed containers because of the danger of pressure build-up resulting from the generation of hydrogen chloride and other gaseous by-products resulting from the decomposition of these compounds that occurs during storage, (2) alkanesulfinyl chlorides have a tendency to decompose by a disproportionation reaction, resulting in formation of the corresponding sulfenyl (S.sup.+2) and sulfonyl (S.sup.+6) chlorides, and (3) the arenesulfinyl chlorides used as starting materials by Levchenko et al. have been known to explode during distillation.
The N,N-dihaloamines and amides and the alkali metal haloamides used by Levchenko et al. and the trimethylsilyl azide used by Bechtold et al. are often high energy compounds, requiring extensive safety precautions during their preparation and handling.
Finally, the sulfinamides, t-butyl hypochlorite and N-chlorobenzotriazole used by Johnson are not readily available from commercial suppliers.
An objective of this invention is to provide a method for preparing organic sulfonimidoyl halides and sulfonimidates using initial reactants that do not require preparing or reacting compounds of tetravalent sulfur. In addition, the initial reactants are available from commercial sources, and the initial reactants are stable during long-term storage and pose fewer problems during manipulation and use.
The present inventors discovered a method for preparing N-triorganosilyl organosulfonimidoyl halides by reacting an N-triorganosilyl organosulfonamide or an N,N-bis(triorganosilyl)organosulfonamide of the formula EQU R.sup.1 SO.sub.2 N[Si(R.sup.2).sub.3 ].sub.p (H).sub.2-p
where R.sup.1 and R.sup.2 each represent a monovalent hydrocarbon or substituted hydrocarbon radical and p is 1 or 2, with a triorganodihalophosphorane, R.sup.3.sub.3 PX.sub.2, where R.sup.3 represents an aryl radical and X is chlorine or bromine.
The sulfonimidoyl halides, R.sup.2.sub.3 SiN.dbd.S(O)R.sup.1 X, prepared in accordance with the present method are useful compounds in themselves. A preferred application of these halides is to convert them to the corresponding sulfonimidate by reaction with a phenol or a fluorinated monohydric alcohol. The sulfonimidate can be condensed to form a particularly useful class of polymers referred to as polyorganooxothiazenes or polyorganooxosulfurnitrides.